Carbonate-hosted Mississippi Valley-type Pb-Zn deposits in Tunisia (eastern Atlasic foreland belt)
Tunisia is the eastern segment of the Atlas mountains ranges that formed during the Alpine orogeny. The Atlasic foreland is in the front of the Tellian fold belt. Zinc and lead deposits in the Tunisian Atlassic foreland occur in Triassic to Upper Miocene dolostones and limestones. Four groups of ore-deposits can be distinguished: (1)(a)Pb-Zn-Cu-As-Hg in the Tellian belt and (b) Pb-Zn in Upper Miocene strata in Upper Miocene basins;(2) (a) Pb-Zn-Sr in Triassic cap-rocks and (b) Pb-Zn in the Upper Cretaceous cover of Triassic evaporates domes; (3)(a) F-Ba-Pb-Zn in Jurassic platform carbonate and (b) Pb-Zn-Ba or siderite in Aptian platform carbonate; (4) F-Ba-Pb-Zn in Jurassic platform carbonates. Replacement of limestone and open-space fillings in karst cavities are the principal types of ore occurrences. Lesser amounts occur as open-space filling of fractures.The ore-forming brines have salinities in the range of 10 to 20 wt％ NaCl equiv. and temperature in the range of 70 to 200℃. Hydrocarbons as oil fluid inclusions or oil seeps are abundant in most the oredeposits. For the genesis of the ore-deposits we propose an orogenically driven circulation of brines in crustal rocks, followed by the ascent and reaction with fluids in the overlaying rocks, as a consequence of the tectonic collisions of the European and African plates.
Pb-Zn ore-deposits pMississippi Valley type Atlassic foreland
S.Boulel
Department of Geology, Resources Mineral Laboratory, Faculté des Sciences de Tunis, El Manar University, 2092 Tunis, Tunisia
国际会议
第八届国际矿床地质会议(Proceedings of the Eighth Biennial SGA Meeting)
北京
英文
19-22
2005-08-18（万方平台首次上网日期，不代表论文的发表时间）